1. Field of the Invention
This invention relates to a photographic light-sensitive material and more particularly, it is concerned with a photographic light-sensitive material having a good film quality.
2. Description of the Prior Art
In the production of photographic light-sensitive materials, it is important to increase the film quality thereof so as to improve the photographic and processing properties. Use of a hardener for gelatin is generally carried out in order to increase the film quality. It is well known as described in Japanese Pat. No. 131,152/1939, Nihon Shashin Gakkai-shi, Vol. 28, p. 195 (1965), Japanese Pat. publication No. 38712/1971 and U.S. Pat. No. 3,597,208 that synthetic high molecular materials containing maleic acid increase the quality of films containing gelatin. Furthermore, it is reported in British Pat. No. 1,137,909, German Pat. No. 1,422,810, British Pat. No. 1,124,284 and French Pat. No. 1,240,768 that synthetic high molecular weight materials containing maleic acid not only increase the film quality, but also are effective for increasing the covering power and preventing halation or static charging.
When a synthetic high molecular weight material containing maleic acid (copolymer) is added to gelatin, however, a marked increase in viscosity and, after the passage of time, even a gelation occur. Therefore, maleic acid copolymers have various uses but the practical use thereof is quite limited. In order to solve this problem, it is necessary to suppress completely the increase in the viscosity of an aqueous solution when a maleic acid copolymer and gelatin are mixed as well as the gelation after the passage of time. In particular, a styrene-maleic acid copolymer has a disadvantage that the viscosity increases markedly when this copolymer is mixed with gelatin and gelation is nearly unavoidable after the passage of time.